A plan or method for dealing with a problem or for achieving a result.

The company's winning formula includes excellent service and quality products.

2017 March 14, Stuart James, “Leicester stun Sevilla to reach last eight after Kasper Schmeichel save”, in the Guardian‎[1]:

Shakespeare has gone back to the formula of last season, by encouraging his players to press high up the pitch and restoring Shinji Okazaki to the starting XI to scurry around between midfield and attack.

(logic) A syntactic expression of a proposition, built up from quantifiers, logical connectives, variables, relation and operation symbols, and, depending on the type of logic, possibly other operators such as modal, temporal, deontic or epistemic ones.